There’s no shortage of reasons for publishers to be excited about on-demand audio as the next platform frontier. But at this point, monetization is probably not one of them.

Even though most publishers don’t yet have audiences big enough to sell on their own, they are finding Amazon to be a relatively permissive partner with Alexa, provided they stay in the lane of delivering news through what Amazon calls Flash Briefings. And they’re beginning to learn what works and what doesn’t.

“The opportunities are large going forward,” said Pat Higbie, the founder of Xappmedia, which has built over 40 active Alexa skills. “Where people are right now is trying to feel out what Amazon will allow.”

Amazon has changed its thinking on monetizing Alexa since its launch. At first, Amazon simply barred developers from using Alexa’s voice to read ad copy, and publishers got around that by having their Flash Briefing hosts read ads aloud. Publishers including The Washington Post, HuffPost and Bloomberg began monetizing this way months ago, with The Washington Post starting last July.

In April, publishers (and advertisers) looking to take advantage of the Alexa devices’ interactive potential got a rude awakening. Amazon revised its rules to bar any ad that promoted third-party products or services, unless those ads were delivered in Flash Briefings, streaming music or radio skills.

Amazon became more restrictive in May, banning any kind of interactivity in its advertising. That move had consequences. Voice analytics service VoiceLabs, which had unveiled a Sponsored Messages ad network that would have allowed advertisers to distribute interactive voice ads across Amazon skills, decided to shut the ad network down within weeks of the change.

While Echo devices are a relatively new feature in the media landscape, some audio formats accessible through Alexa, including digital radio broadcasts and podcasts, are fairly well established. That’s why some publishers have treated the Alexa Flash Briefings as one more place to park audio products they have already developed. A number of radio stations, including those owned by Federated Media, simply add the listeners tuning in through their stations’ Alexa skills to their total digital broadcast audience numbers. And because the ads in those broadcasts are already inserted to the stream by the time they come through the device, Amazon doesn’t touch these broadcasts’ ads.

Not everybody lumps the Amazon audiences in with the rest of their audio listeners. The New York Times, for example, puts a version of The Daily — a short (and daily) podcast that launched in January — on Alexa devices and Google Home, but it doesn’t count its Alexa audience as part of The Daily’s overall reach and doesn’t monetize those listens.

The stringent rules Amazon has put in place limiting third-party promotions has limited publishers’ opportunities to integrate sponsored content into some of the skills they’ve developed for non-news purposes. While HuffPost has baked host-read ads into its Flash Briefings, it’s been able to put sponsored-content questions into the news quiz it offers on Google Home. In March, the publisher added daily questions about the ABC drama “American Crime” into its quizzes.

Separately, two skills Hearst‘s emerging platforms team built for Good Housekeeping and Elle have no clear path to monetization because neither skill is considered a Flash Briefing.

Listener behavior adds another layer of difficulty. With no ad-skipping capability, readers will simply kill a skill rather than wait through an ad, which is why some publishers have already begun to shorten the run time of the advertisements they put out. The Washington Post, for example, has cut the average run time of the ads in its Flash Briefings from 15 seconds to 10 seconds.